Some of the side effects that can occur with doxycycline may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Incidence not known

Back, leg, or stomach pains

bleeding gums

blood in the urine or stools

blurred vision

bulging soft spot on the head of an infant

change in the ability to see colors, especially blue or yellow

chest pain, discomfort, or burning

chills

cracks in the skin

decrease in vision

difficulty breathing

discoloration of the thyroid glands

double vision

general body swelling

heartburn

increased sensitivity of the skin to sunlight

loss of heat from the body

lower back or side pain

nosebleeds

pain or burning in the throat

pain with swallowing

painful or difficult urination

pale skin

pinpoint red spots on the skin

rash with flat lesions or small raised lesions on the skin

red, swollen skin

redness or other discoloration of the skin

redness, swelling, or soreness of the tongue

scaly skin

severe nausea

severe sunburn

sores, ulcers, or white spots on the lips or tongue or inside the mouth

Nervous system

Benign intracranial hypertension resulting in significant loss of vision has been reported.

A 70-year-old female patient with no significant medical history suddenly developed a severe headache followed by vomiting about 15 minutes after the initial dose of doxycycline. The patient also experienced memory dysfunction; she could not remember the events of the afternoon prior to the doxycycline dose and could not retain the information after she was reminded. The incident lasted about 30 minutes and she was transported to the hospital for further evaluation. No further cause, such as intoxication or trauma, could be elicited. Once at the hospital, the patient was able to remember the events of the afternoon and could retain new information, but amnesia regarding the events of the 30 minutes following the onset of the headache persisted. The patient's laboratory results, CT scan, MRI scan, cerebrospinal fluid, and EEG showed no pathology. When the patient was discharged 2 days later, the amnesia for the 30 minutes continued. After elimination of other symptomatic causes, the amnesia was concluded to be due to the doxycycline because of the close relation of the doxycycline dose and the onset of symptoms.[Ref]

Numerous cases of esophageal ulceration have been reported. In most of the cases the patients had taken their medication at bedtime, usually without enough liquid. Patients often present with severe retrosternal pain and difficulty swallowing. Ulcerations generally resolve within a week after discontinuation of the medication. One case report describes severe hiccups of 4-day duration associated with esophagitis following the first dose of doxycycline.

Esophagitis and esophageal ulcerations have been reported in patients receiving capsule and tablet formulations of tetracycline-class drugs. Most took medication immediately before going to bed.[Ref]

In a double-blinded study, doxycycline was found to be more phototoxic than minocycline and demeclocycline. Paresthesias of the body areas exposed to sunlight may be early signs of sunburn reactions.

A case report of a possible photoallergic reaction describes scaly erythema and vesicles on the face and neck associated with doxycycline administration. Upon rechallenge, a flare with erythema, itching and burning occurred in the same area.

Another case report was documented in Australian troops treated with doxycycline 100 mg daily for malaria prophylaxis while on deployment in East Timor, a group of islands within the Malaysian archipelago located close to the equator. Of the 135 troops, 22 exhibited phototoxic reactions to low dosages of doxycycline that resembled severe sunburn with erythematous plaques on the sun-exposed areas. The troops used a sunscreen containing oxybenzone.

An 11-year-old boy treated with doxycycline for brucellosis was evaluated for painless brown nail discoloration. Doxycycline was initiated for brucellosis but stopped when the boy developed photosensitivity, but 15 days after the initiation of therapy brown nail discoloration developed. Other than the brown discoloration, the boy's physical condition was normal and the discoloration disappeared within one month.[Ref]

Professional resources

Related treatment guides

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